If you pay attention, you'll notice something tucked under the lobster and parsley at the Georgetown Seafood House.

It's a jazz quartet.

"Pirate's Hideaway," the room under the restaurant, bills itself as "The Smallest Jazz Club in the World." Its only entrance is just past the raw bar, following the arrow on the handwritten sign that points to "Live Jazz" down the stairs.

"I wanted to call it 'My Living Room," said Michel Sellier, who owns both club and restaurant. He also wanted the Dick Morgan Quartet, the acoustical jazz band that's played there since it opened last November, to be set up right in the middle, so everyone could sit around it. "But that didn't fit in the room. We had to have the furniture remodeled because it wouldn't fit either."

The Hideaway is listed in the phone book; the only advertising is what wafts out the door: a blend of music and garlic.

You might call it cozy. You might call it crowded. That would probably depend on whether you were, on a weekend, one of the lucky 40 seated or one of those lining the stairs waiting for the seat. Because, despite its size and lack of advertising, there are regulars who push past the lobsters on ice and head down for their fill of the jazz: Dick Morgan on piano, Jim West on percussion, Rick Whitehead on guitar and Dave Wundrow on bass Friday and Saturdays (Morgan is not there Monday through Wednesday).

Dinner is served in the club, too; still, cracking a lobster claw as the group hits up Duke Ellington's "Satin Doll" seems a touch rude. But Sellier wants you to feel at home. "Music doesn't start until 9 but you can eat down there or relax. I love jazz and I like the idea of people just relaxing to it, not like at a club that has so many people. I could seat 70 people there at one time but I want everyone to be comfortable." Instead there are not-too-small tables and two couches.

Just like in someone's home, unexpected guests do drop in occasionally. Not Count Basie, whose picture is on the wall because he's a friend of a friend of Sellier's; but a vocalist from his band came a few months ago and just started singing, neither invitation nor microphone needed. "Because the music was just so good," says Sellier, who says too that "Dick Morgan's will play there as long as they want to."

The music is 9 to 1 and the kitchen serves 5:30 to 1 seven nights a week at 3056 M Street NW. The weekend cover is $4; on weeknights there's a $5 minimum.